The invention relates to an intake system for an internal combustion engine of a motor vehicle.
German patent no. DE 196 13 860 discloses an air intake filter unit for an internal combustion engine of a motor vehicle with a tubular space that is connected to a main intake and a secondary intake via intake lines. A sealing device that can alternately close one intake line and open the other intake line is provided in addition. This sealing device is moved by means of an actuating element in such a way that the sealing device closes the main intake and opens the secondary intake when the motor vehicle is immersed in water. This actuating element is operatively linked with a slide valve. The slide valve is arranged in a tube, which is open along its lower end, and is sealed relative to said tube. The slide valve is operatively linked with a permanent magnet. The sealing device is operatively linked with an additional permanent magnet. This permanent magnet of the sealing device is rotatable relative to the permanent magnet of the actuating element.
The disadvantage of this embodiment is that the tube, which is arranged in the engine compartment, requires a considerable amount of space. The tube may not be made too small since the switching point of the arrangement can otherwise not be precisely defined. This mechanical switching arrangement furthermore responds only if the vehicle is immersed into standing water. In case of road spray, the pressure that builds up is insufficient for switching, so that water reaches the intake tract and impairs the functioning of the engine.
It is an object of the invention to provide an air intake system that can be integrated into a small space.
Another object of the invention is to provide an air intake system that prevents snow, road spray or gushes of water from entering the air intake.
These and other objects are achieved by the invention as described and claimed hereinafter.
The intake system for an internal combustion engine of a motor vehicle according to the invention has a first air intake and a second air intake for raw (i.e., unfiltered) air. These two air intakes are combined into a common line, which line communicates with the internal combustion engine. The two air intakes may also be combined directly in front of the internal combustion engine, in which case each air intake has its own components, e.g., its own filter element. Each air intake comprises an opening through which air can flow into the intake system and a line segment, which connects this opening with the line or with other components arranged between the line and the air intake. The air intakes can be closed off with a closure element or valve member, so that air reaches the line communicating with the internal combustion engine through either the first air intake or the second air intake. The valve member completely blocks the respective air intake, so that air can flow into the line only through the unblocked air intake. The valve member can be formed, for instance, by a rotary body with corresponding openings. This rotary body opens the first air intake in one end position and closes the first air intake in a second end position.
The incoming air is either directly or indirectly guided to the internal combustion engine through the line communicating with the internal combustion engine. If the air is indirectly guided to the internal combustion engine, it can be pretreated, e.g., dried or cooled. If the air is directly guided to the internal combustion engine, no further component is arranged in the line.
The first air intake is disposed at a point in the motor vehicle that is advantageous for air intake. The front area is a preferred location since impact pressure is created as a function of the vehicle speed and the air is pressed into the air intake, which improves the filling ratio of the cylinders. Furthermore, the air that is sucked in from the front area is cooler than the air present in the engine compartment. In the front area, however, snow, ice, road spray or splashes of water may also reach the first air intake. Road spray is defined as air mixed with water droplets of any size. Road spray can for example be splashed up from the road by a vehicle traveling ahead or can be produced by rain. The term gushes of water describes a larger amount of water, which may occur in the form of larger splashes or a surge of water, for instance as may be encountered in fording a river. The second air intake is arranged at a point in the vehicle that is less favorable for air intake but is protected against road spray and splashes of water. Preferred locations to arrange this second air intake can for instance be the engine compartment or the ventilation system.
To actuate the valve member, a drive unit connected to a control element is provided. This drive unit can be embodied, for instance, as an electric motor or a vacuum unit and can be actuated by means of the control element. This causes the drive unit to execute a rotary or linear movement that moves the valve member from a first end position to a second end position and thereby seals either the first or the second air intake. The control element is embodied as a moisture sensor with a signal output to control the drive unit. This moisture sensor can of course also be used for feedback control.
The moisture sensor may be adjusted in such a way that it sends a signal to the drive unit even if there is road spray, which already impairs the functioning of the internal combustion engine. This signal causes the first air intake to be closed. At another setting of the moisture sensor, the signal for closing the first air intake is emitted only if the moisture sensor is surrounded by water. The signal of the moisture sensor can be sent to the drive unit either directly or via an electronic element, e.g., the motor control. As soon as the first air intake is closed by the valve member, the second air intake is opened, whereby the internal combustion engine receives combustion air sucked in through the second air intake.
In an advantageous embodiment of the invention the valve member is a pivotable valve. This pivotable valve can for instance be circular, oval or rectangular, so that it closes the second air intake in a first position and the first air intake in a second position. The pivotable valve can be arranged centrally on a valve shaft and can be moved by a rotary movement of the valve shaft. In other embodiments, the valve shaft is arranged along an edge area so as to provide an air intake that is free from interfering contours. To prevent penetration of water into the first air intake, particularly in case of immersion into a body of water, the pivotable valve may be provided with a circumferential seal. Other embodiments are feasible, in which a first pivotable valve is arranged in the first air intake and a second pivotable valve in the second air intake. The two pivotable valves are connected so that they communicate with one another. As soon as the first pivotable valve changes its position, the second pivotable valve also moves, so that one air intake is always open while the other one is closed. This communicating connection of the pivotable valves can be mechanical, e.g., using a strut, or electronic, using a signal that is emitted particularly by the moisture sensor.
In one specific embodiment, the pivotable valve has two pivotable valve parts that are correspondingly connected with one another. These pivotable valve parts can be arranged at a defined angle relative to one another. They can either contact one another directly or be rigidly connected by means of connecting elements. The parallel arrangement of the pivotable valve parts relative to one another represents a special embodiment. The pivotable valve parts can also be locally separated, however, and correspond with one another only via the drive unit. The pivotable valve parts can for instance have a circular, oval or rectangular cross section with one pivotable valve part sealing one air intake. The pivotable valve parts may be provided with a circumferential seal to close the air intakes tightly. If pivotable valve parts are used to close the air intakes, said air intakes can end in the common line in various ways.
The drive unit can for instance be a solenoid that communicates with the moisture sensor. This solenoid can execute an axial or radial motion to move the valve member. As soon as the moisture sensor detects water it sends a signal to the solenoid, which causes the solenoid to move and thus the valve member to change its position. The solenoid responds to the signal within fractions of a second whereby the first air intake is closed before water can penetrate and reach the internal combustion engine. As is generally known, solenoids have an anchor, a spring, a coil, a yoke and an electrical connection.
The moisture sensor is formed by at least two electrically conductive sensor wires spaced at a distance from one another. These electrically conductive sensor wires are made of a material that has low electrical resistance and is therefore a good electrical conductor, e.g., metals or metal alloys. The sensor wires spaced at a distance from one another may extend parallel or at an angle to one another. The sensor wires can have any cross section, e.g., circular or rectangular, and even very small cross sections are possible, e.g., in the range of 0.01 mm2. These small sensor wire cross sections can be created, for example, by applying a metal to a substrate by means of vapor deposition. The two sensor wires are correspondingly connected with an evaluation unit, which can emit a signal to control the drive unit. As soon as a defined current flow between the two sensor wires is exceeded, the evaluation unit generates the signal to close the first air intake.
According to a further embodiment of the invention, the electrically conductive sensor wires are deposited on a substrate, said sensor wires being either embedded in the substrate or placed on top of it. The substrate is made of a material that in its dry state insulates the conductive sensor wires from one another. This material may be designed to absorb water, whereby it becomes electrically conductive. In another embodiment of the substrate, the substrate material is not capable of absorbing water, so that the water is separated in the form of droplets on the substrate. Such a droplet then bridges the electrically insulating substrate material and connects the sensor wires with one another to create a current flow that causes the first air intake to be closed.
In another specific embodiment of the invention, the moisture sensor is arranged in a plane with the first air intake. It can be arranged at a location remote from the air intake, which chiefly comes into contact with water. The valve member is disposed above the moisture sensor at a defined distance, so that a sufficient response time remains between the detection of water and the closing of the first air intake. The moisture sensor is preferably arranged in a location within the engine compartment. As a result it detects the environmental conditions within the engine compartment. When the vehicle drives through water, the moisture sensor is immersed into the standing water simultaneously with the air intake and immediately causes the first air intake to be closed by the valve member, which is arranged at a higher point. Arranging the moisture sensor in the same plane as the first air intake prevents any premature closing of the first air intake, which would occur if the moisture sensor were arranged at a lower point.
In a further embodiment of the invention the moisture sensor is arranged within the first air intake. As a result, the moisture sensor detects exactly the conditions prevalent within the first air intake. It causes the first air intake to be closed by the valve member as soon as water enters the first air intake. The valve member is disposed downstream from the moisture sensor. The distance between the valve member and the moisture sensor is such that after detection of water a sufficient response time remains to close the first air intake before water can flow past the valve member and reach the internal combustion engine. Arranging the moisture sensor within the first air intake ensures that said first air intake is closed only if water actually enters the first air intake. The air is thus taken in via the first air intake, which is more favorable for the internal combustion engine, and the first air intake is closed and air sucked in via the second air intake only if water actually penetrates the first air intake.
In yet another variant of the invention, the moisture sensor can be integrated into the valve member.
According to a further embodiment of the invention, the intake system has a filter element with a filter medium and the moisture sensor is integrated into the filter element. The filter element is inserted into a filter housing in such a way that an untreated area is separated from a treated area forming a tight seal. On the untreated-air side the filter housing communicates with the first and the second air intake. On the treated side, the filter housing communicates with the internal combustion engine. An intake air manifold, which distributes the treated air to the individual cylinders of the internal combustion engine, can be arranged between the internal combustion engine and the filter housing. It is of course also possible to provide two air filters, with one air filter being arranged in each untreated air line. The treated air regions are then combined into a common line.
Since the moisture sensor is integrated into the filter element, it is replaced at the same time as the filter element. Thus, the moisture sensor can be altered through aging processes only within the replacement interval, which ensures that the moisture sensor is highly reliable. The filter element may comprise only the filter medium, e.g., a nonwoven filter material. In other embodiments the filter element has several components, e.g., a combination of a filter medium and an enclosure. This enclosure can be used, for instance, as a seal or a stabilizing frame. The filter element can have any form, but an embodiment as a flat element, particularly a rectangular flat element, or a hollow cylinder is advantageous. The filter medium may be a filter paper, particularly a coated or treated filter paper. The filter medium can, for example, be flat or folded.
In one particular embodiment, the electrically conductive sensor wires of the moisture sensor are connected directly with the filter medium. The sensor wires can for example be glued or woven into the filter medium or cast into the paper pulp during paper production, whereby the precise condition of the filter medium is detected. With increasing penetration of moisture into the filter element, the airflow resistance of the filter medium increases, so that the internal combustion engine receives less air for combustion. In addition, the filter medium, after it can no longer absorb any more water, releases this water on the filtered side, so that water can penetrate into the internal combustion engine. It is therefore advantageous to detect the penetration of moisture into the filter element, so that based on the condition of the filter a signal can be sent from the evaluation unit to the drive unit causing the first air intake to be closed by the valve member.
The sensor wires can be arranged on the filter medium in any form. If the filter medium is folded, the sensor wires can extend longitudinally, diagonally or perpendicularly to the folds and can extend either along a folding edge of the folds or along a surface of the folds. Care must be taken in each of these embodiments, however, that the sensor wires have sufficient non-insulated contact with the filter medium. Furthermore, the sensor wires can be arranged on the untreated or the treated side. If the sensor wires are arranged on the treated side they are protected against dirt. Furthermore, the sensor wires should preferably be arranged at a point on the filter element where the greatest possible penetration of moisture can be expected. This makes it possible to close the first air intake when moisture has penetrated only into this area, while the rest of the filter element is still capable of absorbing water. The smaller the distance between the sensor wires, the less moisture it takes to produce a sufficient current flow, which sends the signal to close the first air intake.
According to a further embodiment of the invention, the filter housing has voltage contacts to supply the moisture sensor with voltage. These voltage contacts can be arranged at any point in the filter housing. The moisture sensor can, for instance, be arranged directly within the filter space of the filter housing or outside this filter space. Since the filter housing is at least partly a stationary component, the arrangement of the voltage contacts on the filter housing can save cables and mounts for the moisture sensor. Also feasible are embodiments in which the sensor wires are connected with the filter housing in such a way that they contact the filter element. When the filter housing is opened, the sensor wires are lifted from the filter element. After a new filter element has been installed, the filter housing is closed again causing the wires to rest against the filter element. As a result, only the used filter element is replaced and all other components can continue to be used.
It is advantageous that the moisture sensor has voltage connections that are inserted into a seal extending around the filter medium. This makes it possible to supply the moisture sensor with voltage by mounting the filter element in the filter housing. The voltage connections can for instance be externally applied to the seal, with corresponding contacts being provided within the filter housing. In this embodiment, the filter element is inserted into the filter housing whereby the contacts of the filter element touch the contacts of the filter housing and thus supply the sensor wires with voltage. A further option to arrange the voltage connections within the seal is to insert the voltage connections into the interior of the seal, which is accomplished when the sealing material is applied.
An advantageous embodiment of the invention provides for the arrangement of a plurality of moisture sensors. For instance, two identically constructed moisture sensors may be provided. These moisture sensors may also be arranged at different locations within the motor vehicle. Also feasible is the use of dissimilar moisture sensors that differ, for instance, with respect to the distance between the sensor wires or the voltage supply. The moisture sensors can be arranged directly side by side or at different locations within the motor vehicle. In one possible arrangement, for example a highly sensitive moisture sensor can be arranged within the first air intake and an insensitive moisture sensor within the engine compartment below the first air intake. This makes it possible to configure different switching variants. As soon as the insensitive moisture sensor is immersed in water it can output the signal to close the first air intake although the highly sensitive moisture sensor has not yet had any contact with water. In a further variant, both moisture sensors come into contact with road spray. The insensitive moisture sensor does not yet emit a signal while the highly sensitive moisture sensor already detects a threshold value.
It is advantageous that the operability of the moisture sensor can be tested upon start of the internal combustion engine. A moisture sensor test that verifies the operability of the moisture sensor takes place as soon as the internal combustion engine is started to ensure that the moisture sensor is indeed operable when required. This operability can be tested, for instance, by a reference value, which is stored in the evaluation unit. To display the status of the moisture sensor for the operator of the internal combustion engine, the moisture sensor may be connected e.g., to a control light, which is extinguished after the sensor test if the sensor operates correctly. If the sensor test is negative and the moisture sensor does not operate as specified, the control light may blink, for example, or be steadily lit. Thus, the operator is informed that the intake system does not operate properly and the first air intake may possibly fail to close in case of water so that for instance driving through water should be avoided and the intake system should be serviced as soon as possible.
In another specific embodiment of the inventive concept, the operability of the drive unit and the valve member can be tested upon start of the internal combustion engine. The drive unit and the valve member are moved each time when the internal combustion engine is started, so that all parts are operable when needed and are not frozen, for instance due to corrosion. The testing of the drive unit and the valve member can be indicated e.g., by a control light, which is extinguished only after successful movement.
These and other features of preferred embodiments of the invention, in addition to being set forth in the claims, are also disclosed in the specification and/or the drawings, and the individual features each may be implemented in embodiments of the invention either alone or in the form of subcombinations of two or more features and can be applied to other fields of use and may constitute advantageous, separately protectable constructions for which protection is also claimed.